The present application relates generally to variable speed drives. The application relates more specifically to a liquid-cooled power semiconductor module in a variable speed drive.
Variable speed drives (VSDs) used for heating, ventilation, air-conditioning and refrigeration (HVAC&R) situations typically use metal, for example, copper, cooling members or cooling blocks for mounting and thermal management of insulated gate bipolar transistor (IGBT) semiconductor switches. The metal cooling blocks are expensive due to high material and labor costs associated with manufacturing such as machining. VSDs may also use plastic cooling blocks for cooling, which reduce materials costs, but plastic cooling blocks do not reduce labor costs, since the plastic cooling blocks also require machining. Plastic cooling blocks typically are not suitable for injection molding processes for manufacturing because of their large size and low annual usage quantities. The size of a particular cooling block is determined by the number of components, for example, modules, which are mounted to the cooling block. A cooling block may be mounted to two, to as many as six or more modules. Each module mounted to the cooling block requires multiple channels to be machined into the cooling blocks, forming a tub. Thus, a single cooling block may have six or more tubs, depending on the number of modules mounted thereto. Due to the physical size of the cooling block, the process of injection molding to form the cooling blocks is rendered impractical. Also, VSDs covering applications ranging from low horsepower to high horsepower require cooling blocks with two to six tubs. In such applications, low quantities of each individual size are used, thereby causing large costs for injection molding each individual sized cooling block.